Clostridioides difficile infections caused by hypervirulent strains: a single-centre real-life study

Background and purpose: Clostridioides difficile infection (CDI) is a leading cause of healthcare-associated infections worldwide, with hypervirulent strains linked to severe disease and higher mortality. This study aims to analyze the epidemiology of CDI at a tertiary-care hospital in Italy and compare clinical outcomes between patients infected with hypervirulent and non-hypervirulent strains.

Methods: A retrospective comparative study was conducted on patients diagnosed with CDI at ASST Spedali Civili di Brescia, Italy, from January 2015 to June 2023. Hypervirulent strains were identified using the GeneXpert assay as positive for cytotoxin gene (tcdB), binary toxin genes (tcdA and tcdB) and a single nucleotide deletion at position 117 in the tcdC gene and compared to a randomized matched control group with non-hypervirulent CDI. Clinical data were collected and analyzed, with multivariate logistic regression employed to identify risk factors for hypervirulent CDI.

Results: Of 1,059 positive C. difficile specimens, a statistically significant trend between January 2015 to June 2023 was found in the increasing incidence of CDI cases per 1,000 hospital admissions and 10,000 bed-days. Notably, a remarkable increase of hypervirulent strains was recorded in 2021 and 2022 when compared to previous years. A total of 130 patients were analyzed: 62 (47.7%) with hypervirulent CDI and 68 (52.3%) controls. Hypervirulent CDI was associated with higher 30-day mortality (18% vs. 5.8%, p = 0.03). Multivariate analysis showed that hypervirulent CDI significantly increased 30-day mortality risk (OR = 9.915, CI = 2.37-61.05, p = 0.005) and that prior antibiotic therapy was a significant risk factor (OR = 5.49, CI = 1.19-39.96, p = 0.047).

Discussion: Our epidemiological data, while suggesting a potential resurgence in CDI transmission during COVID-19 pandemic, are derived from a single-center experience with limited generalizability to the broader population. Nonetheless, they highlight the need for strengthened antimicrobial stewardship and national surveillance systems to effectively monitor and manage these strains.